Vivek Ramaswamy once again proved that he is the smartest guy in the room.

He got out while the going was good.

Hardly had the Iowa GOP presidential caucus vote come in, and then Vivek was out.

And as he suspended his campaign for president after coming in a distant fourth, he endorsed Donald Trump, the walkaway winner of the Iowa Republican presidential caucuses. Smart.

Unlike the two remaining GOP challengers to Trump, the 38-year-old Ramaswamy will live to fight another day, especially if Trump, as expected, wins the GOP nomination for president.

Trump, he told his supporters in Iowa, “will have my full endorsement for the presidency.  And I think we are going to do the right thing for this country. And so, I am going to ask you to follow me in taking our America First movement to the next level.”

And with that, Vivek left for New Hampshire and campaigned for Trump, who is comfortably ahead in the polls, although being pressed by former UN Ambassador Nikki Haley.

No sooner did Vivek arrive than he launched a fiery speech on Trump’s behalf at a Trump rally in Atkinson, NH.

With Trump, 77, looking on like a proud father, Vivek said, “We’re in the middle of a war in this country” between “those who love the United States and a fringe minority who hates this country and what we stand for.”

“We need a commander in chief who will lead us to victory in this war.”

In out trumping Trump, Vivek, in a series of “truths,” said, “There are two genders in this country, period. Fossil fuels are a requirement for human prosperity—drill, frack, burn coal, embrace nuclear energy. Reverse racism is racism.  An open border is not a border. Parents determine the education of their children.”

Trump’s huge win in Iowa, followed by a victory in the New Hampshire primary Tuesday, will all but assure him of the nomination for president.

And Vivek, the successful and articulate biotech entrepreneur, could be Trump’s vice-presidential running mate and be in a position to succeed Trump as president.

At the very least, Trump will no doubt want to keep the articulate, idea-sprouting Ramaswamy around in one position or another. He has been the surprise of the campaign.

Unlike Florida Gov. Ron DeSantis and Nikki Haley, who burned their bridges with Trump, Vivek, who has a lot in common with the former president, was always in Trump’s corner.

At one point in the campaign, Vivek called Trump “the best president in the 21st Century.”

Flattery with Trump will get you everywhere.

Vivek’s decision to drop out and endorse Trump was in sharp contrast to the bitter way former New Jersey Gov. Chris Christie bailed out of the race, attacking Trump all the way out the door.

The difference between Vivek and Christie is that Christie, who has no credibility when it comes to Trump, cannot do for Haley what Vivek is doing for Trump. An endorsement by Christie at this point would be a kiss of death.

While DeSantis came in a distant second in Iowa, he trails badly in New Hampshire and will soon also drop out, leaving Nikki Haley as Trump’s only GOP challenger.

And while DeSantis claimed he got his “ticket punched” in Iowa, he practically knocked himself out.

For Haley to remain a challenger to Trump, who dominates the Republican Party, she will need a miracle win in New Hampshire just to stay alive in her self-described “two-person” race.

That miracle will only happen if there is a surge of anti-Trump Democrats and unenrolled New Hampshire voters who turn out and take a Republican ballot to vote for her.

But it doesn’t matter. There is no stopping Trump.

Trump is coasting to the nomination.  And Vivek caught the last train to the coast.

Peter Lucas is a veteran Massachusetts political reporter and columnist.